BERLIN (AP) — A local branch of German Chancellor Angela Merkel's party says it received a 28,000-euro ($33,000) donation from Azerbaijan's state oil and gas company that was later ruled illegal by parliamentary authorities.

The conservative Christian Democratic Union's Frankfurt branch took the donation from the German branch of SOCAR in 2012.

The party said Thursday the branch wasn't aware at the time that it might be illegal as a foreign donation. Parliamentary officials later ruled it was, after party headquarters in Berlin asked for legal advice.

News agency dpa reports that the party says it immediately paid the money to parliament. It says it didn't face any punishment because it wasn't aware at the time that the donation wasn't acceptable.

It wasn't clear why SOCAR made the donation.